Package build times take too long

[esteve]

Building the entirety of Autoware takes too long, at least 24 hours. This may be alleviated by:

• Using a more performant machine, we're currently using a t3.xlarge, but something with more memory or a faster disk may improve the situation
• Parallelize build step. Packages are built sequentially, and although objects are compiled in parallel, packages are built one by one, there's a chance that building packages in parallel may provide some speedups

[esteve]

I've changed the instance type for the buildfarm to c5.2xlarge in https://github.com/autowarefoundation/autoware-deb-packages/pull/37/commits/9618533e22b4ec90141e6cf9dfc6cc095b323fc7 , which seems appropriate for compiling code.